Abstract:
In this paper the interaction of hydraulic and mechanical dynamics, the inter-actuator
and inter-link interactions in an excavator are modeled using bond graphs, and then simulated
on a MATLAB/SIMULINK environment. Bond graph method was chosen as the modeling method
because, firstly, it is a domain-independent graphical method of representing the dynamics of
physical systems. Therefore, systems from different engineering disciplines can be described in
the same way. Secondly, the available literature shows that the method being relatively new has
not been thoroughly applied to model the dynamics of nonlinear systems such as excavators. A
complete bond graph dynamic model of the excavator was obtained by coupling the mechanical
and hydraulic models using appropriate Manipulator Jacobians which were treated as Modulated
Transformer Elements. The causal bond graph model of the excavator was expanded into block
diagrams and simulated on MATLAB/SIMULINK to determine the transient and steady state
responses of the system. From the responses obtained, the model developed was found to
capture the inter-component interactions and also the interaction between the hydraulic and
mechanical dynamics. Therefore, the model developed can be used to design control laws
necessary for controlling the dynamics and motions of the excavating manipulator.
